Quote table names.
Commit transactions containing SELECT statements.
Map NULL values in sql to NaN.
Cleanup.
Working IsDefined filter.
Sql attributes use to_sql instead of get_value_from.
Support for negate in IsDefined filter.
Store column names in filter.
Moved code that converts columns indices to sql from filter to table.
Simplified SqlRowInstance.
Implemented HasClass on sql.
Merge branch 'master' into filters